1. Field of the Invention
The present invention relates to orthotic medical devices and more specifically to a foldable adjustable night splint which can be used for treating and facilitating the treatment of a variety of conditions including pain in the foot and heel caused by contracture of the plantar fascia and/or the Achilles tendon, treatment of hip ailments, and post-surgery treatment of the foot.
2. Background
Simply put, the human foot takes the brunt of the impact of every step experienced by an individual. It is also likely that the single largest source of complaint for foot ailments is related to heel pain. One source of heel pain commonly observed is due to a condition known as recalcitrant plantar facitis. Plantar facitis occurs in the plantar fascia, a fibrous membrane disposed longitudinally across the bottom of the foot. The plantar fascia is attached at the heel bone, more specifically to the inner tubercle of the os calcis. The plantar fascia becomes broader and thinner as it extends longitudinally across the bottom of the foot, eventually dividing near the heads of the metatarsal bones into five processes, one for each of the five toes.
The strongest ligament in the body is the plantar fascia, a fibrous band of tissue that starts on the bottom surface of the heel bone and extends forward on the bottom of the foot to just behind the toes. Its function is to protect the softer muscles and tissues of the bottom of the foot from injury, as well as to help maintain the integrity of the foot structure itself. If the fascia becomes stretched or strained, the arch area, as well as about the heel bone, become tender and swollen. This inflammation is called plantar facitis and is painful from the heel throughout the arch up into the Achilles tendon. These patients usually have tight and inflexible heel cords, a condition that is referred to as Achilles tendon tightness.
When the heel cord is tight, it causes compensation in the foot with over-pronation of the foot during weight bearing. The pain is consistently worse when you first get up in the morning and at the end of the day. The pain usually lurks in the heel pad and may include the arch ligament. The natural tendency is to ignore the symptoms of the pain at first.
Heel pain like plantar facitis is often times caused by contracture of the Achilles tendon and the plantar fascia, which can occur at night during sleep or during daytime inactivity. The Achilles tendon is the strongest and thickest tendon in the human body. The Achilles tendon begins at or about the middle of the posterior side of the leg extending downward towards the heel, narrowing as it progresses towards its point of insertion at the posterior surface of the os calcis. When an individual is standing, walking, running or even sitting in a position in which the feet are in contact with the floor or other surface, both the plantar facia and the Achilles tendon are extended to varying degrees depending of course on the nature and intensity of the activity. During sleep, an individual has a natural tendency to plantar-flex the ankle joint beyond the position which is normal during walking, standing or sitting with one's feet on the floor. Plantar flexion is when the bottom of the foot is extended so as to form an angle with the lower leg of greater than 90°. Dorsiflexion is the opposite motion; when the foot is moved to a position in which the bottom of the foot forms an angle with the lower leg of less than 90°, this is dorsiflexion.
As a result of plantar flexion during the night, the plantar facia and the Achilles tendon contract from their size and dimension normal to the walking, standing or sitting positions. Upon arising, the plantar facia and the Achilles tendon are once again extended and stretched when the feet and ankles resume a normal position associated with walking or standing. Typically, it is when an individual arises following sleep or a period of extended recumbency that the effects of heel pain associated with plantar facitis, with or without the associated Achilles tendon contracture, are observed. In a significant number of cases, the pain has been described as substantial.
Various theories explain the constant pull of the plantar fascia at the insertion of the heel bone. The plantar fascia and intrinsic muscles can cause spurs or tearing of the fascia at the insertion. With continued pull, subperiosteal bleeding can produce calcification leading to new bone. Other theories are constant stress of the fascia with excessive stress at the insertion forming new connective tissue with the tissue going from fibrocartilaginous tissue to cartilaginous to bone. A reference to the thickening of the plantar ligaments is found as early as 1859 in a dissection of a flat foot by Dr. Wood.
In various types of occupations, sedentary work may produce atrophy and degeneration of the shock absorption ability of the heel's fat pad. Occupations which produce over use of tissue, which is stressed beyond its physiologic limits, such as working at a factory machine or the static loading exposure of welding, may also cause fat pad atrophy and degeneration from long, unnatural hours of standing on hard surfaces owing to the degeneration of the plantar fascia.
Plantar facitis is a condition characterized by tenderness located at or near the point at which the plantar fascia attaches to the heel bone, or the os calcis. This condition has been traditionally treated in a number of ways, including non-steroidal anti-inflammatory medicines, cortisone injections, shoe modifications, physical therapy, and even surgery.
Plantar facitis is referred to in a book written by Dr. Scholl in 1915, as “policeman's heel.” Reference can be found in literature on heel pain before 1900. Authors writing about the conditions affecting the foot referenced it as pain of various courses from systemic disease to pain related to the plantar fascia. In 1860, Zacharie discussed a condition affecting the heel in which patients had greater pain in the morning than after standing and walking for one or two hours. In 1900, Plettner noticed inferior heel spurs on patients' radiographs. After that, many theories were put forth on the cause of heel pain and plantar facitis and the amount of references in the literature had more prevalence in this time. In 1915, Dr. Scholl indicated that a flat foot usually accompanied painful heel pain, giving us the revelation that there was a correlation between pronation and painful heels.
The earliest records reviewed which found treatment for heel pain, was in a 1915 article by Waechter and Sonnenschein in which they used felt aperture pads for the treatment of painful heel pain. Dr. Scholl in 1915 advocated the use of a metal orthotic called the Trispring. Metal was placed into the arch to support it and prevent elongation of the arch and a leather top was applied over the metal. Dr. Carl Bergman, in his orthopedic lecture notes taken at the Illinois College of Chiropody in 1919, suggests the use of a sponge heel pad in the shoe for the local relief of heel pain.
Favorable results for the treatment of plantar facitis have been observed in a study that employed night splints in connection with other non-surgical therapeutic measures to treat this condition. See Wapner and Sharkey, “The Use Of Night Splints For Treatment Of Recalcitrant Plantar Facitis,” Foot and Ankle Vol. 12, No. 3, December 1991. The night splint consists, essentially, of a boot-like structure that is strapped to a patient's lower leg and foot, holding the foot relative to the lower leg in a position such that the ankle joint is held in slight dorsiflexion. In so doing, both the plantar fascia and the Achilles tendon are slightly extended and are not allowed to contract during the night. The use of night splints, together with the variety of other elements of treatment including anti-inflammatory medications, physical therapy, and foot cushions for use during the daytime, has proved beneficial in the treatment of plantar facitis.
It is desirable to have an orthosis that has the possibility of inducing inversion or eversion of a patient's foot. Inversion is when the bottom of the foot, the plantar surface, faces more toward the midline of the body. Eversion is motion of the foot in which the plantar surface of the foot is tilted so as to face further away from the midline of the body.
One method of treating such conditions is through the use of splints. An example of the types of splints that are used to treat these conditions are custom molded ankle-foot orthosis constructed of polypropylene which were described in a study by Wapner/Sharkey as costing each patient approximately $200.00.
It is suggested that the relatively high price of the splints used in the Wapner-Sharkey study is due in part to the requirement that custom molding is required to form the splint to conform to the patient's anatomy. This individualized process then also requires that a custom molded orthosis can be used by only one patient. Various other splints are advertised for treatment of plantar facitis that also typically consist of a molded splint or a combination of molded plastic and metal framework, with the dorsiflexion set at 5°.
Although similar in appearance to foot and ankle casts, also called walking casts, a night splint for the treatment of plantar facitis is only superficially similar to a walking cast. A foot or ankle cast is made so that the force vector of the patient's weight passes vertically through the cast and the patient's leg when he/she is standing. In the medical industry, no walking casts are made that do not place the bottom of the patient's foot at a 90° angle to the patient's leg, which is consistent with a vertical force vector. Thus, no walking casts are built to induce and maintain dorsiflexion or plantar flexion. In addition, a walking cast is made to provide the patient with a weight-bearing region forward of the heel, on which the weight of the body is placed when walking, and from which the patient can pivot forward when taking the next stride. The bearing and pivoting structure can be a rounded knob under the mid region of the foot, or it can be a rounded surface which covers the bottom of the cast from heel to toe. A walking cast may also have a cushioning region directly under the heel to absorb some of the shock of walking.
Walking casts are not made to wear in bed at night, and are not made to induce a stretching effect on tendons. They are made to provide support to healing ankle and foot joints and bones, and to control the motion of these healing joints and bones while healing takes place.
To treat plantar facitis, it is necessary to use considerable force to counteract the strong muscles and tendons of the lower leg and foot. If this force is applied improperly, pressure points can result, thus causing discomfort and complications for some patients.
Some patients have reduced blood circulation or sensation in the feet, such as patients with diabetes, vascular insufficiency, polio, stroke, trauma, or neurological problems. In such patients, if they need to use a night splint for treatment of plantar facitis, it is important to minimize the pressure points exerted by the night splint on the patient's foot, while still exerting the necessary force on the foot and lower leg structure. The night splint must also not bruise or scratch the collateral leg during sleep, must not soil or tear bedding, and must be compatible with a sleeping partner. Walking casts are not designed to accomplish these objects.
Another ailment for which a night splint is needed is calcaneal apophysitis. This is typically of a problem which presents in juveniles. It is basically a case of the bones of the leg and foot growing faster than the connective tissue, such as the plantar fascia and Achilles tendon, and the heel bone is immature and somewhat soft. These two tendons are put under strain and cause heel pain. Treatment of calcaneal apophysitis has proven to be very successful using a night splint. The night splint prevents foot drop during sleep, and helps lengthen the two involved tendons.
Paratendon tendonitis is another condition for which a night splint is needed for successful treatment. The paratendon is a thin sheath-like covering of tendons. The lining of this structure can become inflamed, and require nighttime stabilization to immobilize the foot and lower leg, and treatment.
Achilles tendonitis is another condition for which a night splint is needed for successful treatment. Achilles tendonitis can result from overuse of the tendon in sports activities, and can also result from a number of inflammatory diseases, of which rheumatoid arthritis is one. Use of a night splint is an effective treatment for this ailment, since immobilizing the Achilles tendon without allowing night drop or contracture of the tendon is the best treatment.
Another area where a night splint is needed is after various surgeries on the hip. After hip replacement, for instance, it is desired that the involved hip joint remain absolutely immobile. What is needed is a device that immobilizes one or both feet and lower legs, so that the hip joint is not moved.
Another situation that requires the use of a night splint is when surgery has been performed on tendons in the foot. If the tendons worked on are on the medial side of the foot, it is desirable for the foot to be held in an inverted position (with the plantar surface facing toward the midline of the body), which relieves strain on the affected tendons. If the tendons worked on are on the lateral side of the foot, an everted position is desirable.
Night splints function best when they can be used on a continuous ongoing basis, thus allowing the tendons to be appropriately stretched into a desired position. One problem that exists with walking casts and similar devices is that they are bulky and are difficult to store in a desired position. Another problem is that such devices have an upper portion and a lower portion that is configured in relatively fixed positions relative to one another. This results in many of the devices shown in the prior art being large and bulky and not easily stored for transport or storage. As a result of this phenomenon, many times the individuals who should utilize such devices, fail to do so. In addition, this fixed configuration limits the flexibility and functionality of the device in treating various conditions where the desired positioning of the foot and the lower leg are different from the positioning which is available in the fixed configuration.
Accordingly, it is an object of the invention to provide a flexible selectively adjustable orthosis which is suitable for use on a patient's foot and lower leg during the night, as a night splint for the treatment of plantar facitis, Achilles tendon problems, hip immobilization, post-surgery treatment of the foot, and other conditions.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.